Honda is secretly working on a VVT ( Variable Valve Timing) equipped Fireblade because of the more stringent emission norms, it is a difficult challenge of extracting more power while adhering to the ever-tightening grip of environmental agencies.
But why variable valve timing? Superbikes rely on extracting maximum power within set limits. Without the addition of a supercharger this can only be achieved by increasing the revs. This raises the problem of valve-timing. A high-revving engine requires a lot of valve overlap. A ‘valve overlap’ is a moment when both the intake & exhaust valves are open during the end of the exhaust stroke. This helps in venting out the exhaust gasses and fill the chamber again with a fresh charge.
The overlap works perfectly well during higher revs. However, during low revs when the engine speed is low, the overlap can give enough time to the unburnt fuel to escape through the exhaust valve before its closed. This can result in loss of efficiency and pollution. Honda is working on a system similar to that of BMW’s ShiftCam technology, which works by moving the camshaft from side to side, disengaging one set of cam lobes to bring a more aggressive lobe at higher revs.
Honda’s system seems to be using the cam switching technology on both the intake as well as exhaust camshaft. Honda’s system will also use outer sleeves on every camshaft of every cylinder. Considering there’s always an intake and exhaust valve open in an inline-four engine at any moment, these lobes cannot be switched on until the valves are closed. This will allow a further boost in performance while keeping emissions under check.
Article Source : ZigWheels